1. Field of the Invention
The present invention relates to a throttle control device equipped with a throttle valve for controlling a flow rate of a fluid, in particular, to a throttle control device for controlling the flow rate of air, for example, intake air to be supplied to an automotive engine.
2. Description of the Related Art
Japanese Laid-Open Patent Publication No. 2001-132495 discloses a conventional throttle control device. In the throttle control device disclosed, a throttle valve arranged in an intake passage formed in a throttle body is rotated by a motor. Due to the rotation of the throttle valve, the intake passage is incrementally opened and closed to thereby control the intake air amount. The throttle body is equipped with a bore portion forming the intake passage and a motor housing having a motor accommodating space for accommodating the motor. Pages 3 and 4 and FIG. 1 of the above-mentioned publication are to be referred to.
In the conventional throttle control device, the motor accommodating space in the motor housing of the throttle body is barely large enough to accommodate the motor, with a small gap being left therebetween. Thus, the heat generated from the motor is mainly dissipated by utilizing the heat conductivity of a material forming the throttle body. Thus, when the material forming throttle body is of a low heat conductivity type of material, such as a resin material, there is a concern that the dissipation of the heat generated by the motor is being impaired.